To simplify a hydrogen-producing treatment using anaerobic microorganisms.

The hydrogen-producing apparatus 100 comprising organic wastes 103, a treating tank 102 for receiving anaerobic microorganisms (not displayed) for degrading the organic wastes 103 to produce the hydrogen, and a hydrogen-recovering portion 130 for recovering the hydrogen produced in the treating tank 102, is characterized by disposing a ventilation hole 105 in the treating tank 102 to open the treating tank 102. The hydrogen-producing apparatus 100 further has a gas trap 104 disposed in the treating tank 102.